The present invention relates to belt clamping apparatus, and more particularly to a belt-through clamping apparatus utilizing a lever with a simplified clamp bar to clamp the belt with substantially uniform clamping force in all directions across the clamping area.
Recently, there has been a development in the industry to provide a belt-through clamping apparatus for the safety belt harness. The belt passes through the apparatus as the belt travels from the retractor assembly and turns to go across and into restraining engagement with the occupant of the vehicle. This additional clamping apparatus, most commonly associated with the shoulder safety belt and positioned adjacent the top of the B-pillar of the vehicle, is used to absorb some or all of the load caused by the restraining force of the belt on the occupant in an accident. Such a clamping apparatus can be made load-sensitive at any desired level and can be used either in conjunction with a locking belt retractor or with a non-locking retractor.
In order to provide efficient clamping of the belt, it has previously been found necessary to provide some aligning or compensating means to offset variations in the belt thickness, as well as to compensate for manufacturing tolerances in the parts. When this is done, a substantially uniform force is applied by the clamp bar substantially across the full area of the clamping surface. One successful clamping apparatus of the self-aligning type is disclosed and claimed in the prior U.S. patent application to R. C. Pfeiffer et al. entitled "Seat Belt Clamp Apparatus and Occupant Restraint System," Ser. No. 10,455, filed Feb. 8, 1979, and assigned to the assignee of the present invention. While this prior clamping apparatus met the objectives set forth, the arrangement required the clamping lever to be mounted on a resilient pivot pin. In such an arrangement, the resilient pin mounting acts to cause the entire clamping lever to turn or skew in the direction transverse to the belt in order to compensate for variations across the belt, such as a lateral variation in the belt thickness, as mentioned above. However, since the belt itself travels around and over the clamping lever to actually institute the clamping force, it is possible that false skewing action could be induced by the belt, thus giving a false alignment movement to the lever and allowing less than the full compensating action to the clamping bar. Furthermore, the concept of resiliently mounting the lever adds considerable expense to the cost of this prior belt-through clamping apparatus, not only in initial parts costs, but also in the assembly process.
Thus, it is a first and primary object of the present invention to provide a belt-through clamping apparatus in which the compensating action of the clamping lever is independent of the mounting shaft for the lever.
It is another and related object of the present invention to provide an improved self-compensating clamping apparatus that provides maximum uniformity of force across the full clamping surface, but is also low-cost and easy to manufacture.
It is another object of the present invention to provide a belt-through clamping apparatus in which the clamping element engages the pivotal clamping lever at a point contact to allow aligning and compensating movement in all directions, both in the direction of the belt and transverse to the belt, as well as in all directions inbetween.